1. Field of the Invention
The present invention relates to an optotype presenting apparatus arranged to present test optotypes for testing a visual function of an examinee's eye.
2. Description of Related Art
An optotype presenting apparatus arranged to display vision test optotypes (charts) on a display such as a liquid crystal display and present the optotypes to examinee's eyes has ever been known (for example, see Jpn. unexamined patent publication No. 2006-42978). The optotype presenting apparatus of this type is located in use at a 5-m distance or others for a far vision test.
Meanwhile, the apparatus configured to display the optotypes on the display can present various kinds of optotypes and quickly switch to another on the display.
The case where the vision test optotypes for almost equal visual acuity are selectively displayed in almost the same position of the display is mentioned below. In this case, when an optotype or chart is quickly switched to another, an examiner and an examinee may not instantly perceive that the optotype or chart has been switched to another. Thus, a test could not be conducted smoothly. In the case where Landolt ring optotypes or tumbling E optotypes are selectively displayed by changing only their orientations, particularly, it is likely to be more difficult for the examiner and the examinee to perceive the optotype or chart having been switched as the optotypes are smaller in size.